This invention relates to a handled plastic container in which the container is formed by blow moulding a preform and the handle is separately formed and then connected to the container during the container forming process.
Plastic containers for holding liquids including beverages and other domestic liquids are in wide spread use. During the 1980's plastic largely replaced glass as the material of first preference for the packaging of carbonated soft drinks. Plastics such as polyethylene terephthalate (PET) offer significant savings when compared with glass in packaging such products. Plastic is lighter than glass and plastic bottles are cheaper to make and cheaper to transport than glass bottles. In addition, there are clear safety advantages when using plastic given the inherent problems with breakages when using glass. Plastic containers are also in wide use for products such as detergents and fruit juices. Such products are generally packaged in one or two liter containers with relatively large outlet openings. For ease of pouring, containers such as those made from PVC often include a handle. In the past, the handle in plastic containers formed by extrusion blow moulding have been provided by blow moulding a hollow and integral handle portion into the container side wall. Given the constraints of container design, such handles are generally quite broad and often leave little room for one to firmly grasp the inside of the handle. Special moulds are required in the production of such bottles, they arc more difficult to blow mould than a non handled bottle and there are difficulties with stress concentrations leading to possible container failure in the areas near the junction of the handle with the rest of the container.
In addition, it has not been generally possible to economically produce such handled bottles from synthetic polyesters such as PET. To extrusion blow mould PET it would be necessary to use a resin having a high intrinsic viscosity (i.e. well over 1.0). Such containers would not have the same degree of side wall orientation as a container stretch blow moulded from a preform. If an integral handle was formed in a PET container formed from a preform, special cutting tooling would be required to remove the flashing formed between the container side wall and the integrally formed handle due to the high orientation of the material.
An alternative is the use of a separate handle joined to the container. If a separate handle is utilised it is possible to injection mould a handle which is narrower and thinner than the integral handles of the previously described blow moulded containers and if adequately attached to the container such handle designs are more effective and easier to use.
Various attempts have been made to attach separate handles to blow moulded containers formed from preforms but these have not been altogether successful. One difficulty has been inadequate engagement of the handle with the blow moulded container. A further difficulty has been the relative slowness of the processes used to produce such containers.
It is an object of the present invention to provide a method of securing a separate handle to a plastic blow moulded container which enables relatively rapid manufacture and which leads to the production of a handled bottle where the handle is firmly secured.